<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title>getElementsByTagName获取checkbox进行全选</title>
		<style type="text/css">
			#myTable{ width: 900px; margin: 0px auto; background-color: #008000;}
			#myTable td,#myTable th{ background-color: white;}
			#myDiv{width: 900px; margin: 0px auto; height: 30px; line-height: 30px; 
			text-align: center;}
		</style>
	</head>
	<body>
		<table cellspacing="1" id="myTable">
			<tr>
				<th width="200">
					<input type="checkbox" id="selAll" onchange="" />全选
					<input type="checkbox" id="selAll" onchange="" />反选
                </th>
				<th width="200">姓名</th>
				<th width="200">性别</th>
				<th width="200">专业</th>
				<th width="200">爱好</th>
			</tr>
			<tr>
				<td><input type="checkbox"/></td>
				<td>刘备</td>
				<td>男</td>
				<td>软件开发</td>
				<td>抽烟</td>
			</tr>
			<tr>
				<td><input type="checkbox"/></td>
				<td>关羽</td>
				<td>男</td>
				<td>国际贸易</td>
				<td>喝酒</td>
			</tr>
			<tr>
				<td><input type="checkbox"/></td>
				<td>张飞</td>
				<td>男</td>
				<td>园林设计</td>
				<td>烫头发</td>
			</tr>
			<tr>
				<td><input type="checkbox"/></td>
				<td>赵云</td>
				<td>男</td>
				<td>平面设计</td>
				<td>抽烟</td>
			</tr>
			<tr>
				<td><input type="checkbox"/></td>
				<td>黄忠</td>
				<td>男</td>
				<td>影视制作</td>
				<td>玩游戏</td>
			</tr>
			<tr>
				<td><input type="checkbox"/></td>
				<td>小乔</td>
				<td>女</td>
				<td>高级护理</td>
				<td>唱歌</td>
			</tr>
		</table>

		<script>
			var count = 0;
			//全选
			document.getElementsByTagName('input')[0].onclick = () => {
				if (count == 0) {
					for (let i = 2; i <= 7; i++) {
						document.getElementsByTagName('input')[i].checked = true;	
						count++;			
					}
				} else {
					for (let i = 2; i <= 7; i++) {
						document.getElementsByTagName('input')[i].checked = false;				
					}
					count = 0;
				}
			}
			//反选
			var input;
			document.getElementsByTagName('input')[1].onclick = () => {
				for (let i = 2; i <= 7; i++) {
					input = document.getElementsByTagName('input')[i].checked;
					if (input == true) {
						document.getElementsByTagName('input')[i].checked = false;	
					}else{
						document.getElementsByTagName('input')[i].checked = true;	
					}
				}
			}
		</script>
	</body>
</html>